E08
Cointra Flow Temperature Too High / Primary Overheat

Furnace shows E08, burner shuts down, fan may continue to run.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Insufficient airflow across heat exchanger, Blocked heat exchanger fins, Circulation fan failure, Incorrect gas rate (overfiring)

How to Fix / Troubleshooting

Safety: Turn off gas and power. Allow the furnace to cool fully.

Steps:

  • Check for blocked outlets: Ensure all warm air outlets are open and not obstructed.
  • Inspect circulation fan and housing: Remove dust buildup from the fan wheel and housing using a soft brush and vacuum. Verify the fan spins freely.
  • Clean heat exchanger: Carefully vacuum dust and lint from the heat exchanger surfaces. Do not use sharp tools that could damage fins.
  • Reset and test: Restore power and gas, then call for heat. If E08 recurs quickly, stop using the furnace.

Professional checks: A licensed technician must verify gas input rate with a manometer, check combustion analysis, and ensure the fan speed and control settings are correct. Overfiring or poor combustion can be dangerous and must be corrected professionally.

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Repair Difficulty

Hard 4/5

Required Part

Circulation Fan Motor
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